I wondered myself if the barrel could have been twisted. I stopped worrying after I shot it and got solid consistent groups.
---------- Post added at 04:30 PM ---------- Previous post was at 04:27 PM ----------
I wonder what the tolerance was. Any variation in timing would be compensated for at the rear sight when zeroing. How much is too much? Perhaps war-time standard was that if the rear sight base could be secured, it was good enough. The cant is mostly noticeable because of how far over the rear sight must be to zero.